Dumbbell



FIG. 1 is a perspective view of a dumbbell of my design;

FIG. 2 is a left side elevational view thereof, the right side elevational view being a-mirror image thereof;

FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image thereof; and,

FIG. 4 is a top plan view thereof. 

The ornamental design for the dumbbell, as shown and described. 